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KentuckyFC writes "One of the great challenges in physics is to unite the theories of quantum mechanics and general relativity. But all attempts to do this all run into the famous 'problem of time' — the resulting equations describe a static universe in which nothing ever happens. In 1983, theoreticians showed how this could be solved if time is an emergent phenomenon based on entanglement, the phenomenon in which two quantum particles share the same existence. An external, god-like observer always sees no difference between these particles compared to an external objective clock. But an observer who measures one of the pair — and so becomes entangled with it--can immediately see how it evolves differently from its partner. So from the outside the universe appears static and unchanging, while objects that are entangled within it experience the maelstrom of change. Now quantum physicists have performed the first experimental test of this idea by measuring the evolution of a pair of entangled photons in two different ways. An external god-like observer sees no difference while an observer who measures one particle and becomes entangled with it does see the change. In other words, the experiment shows how time is an emergent phenomenon based on entanglement, in which case the contradiction between quantum mechanics and general relativity seems to melt away."

The theory requires no outside, God-like, observer, nor does it propose one. The point is that time is measured by "events" and "events" occur when the quantum states of two systems become entangled, but only to the systems that became entangled. To an "observer" that has not become entangled, a system is static and no event has occurred.

In the Copenhagen interpretation, one would say that according to the entangled observer the "wavefunction has collapsed" whereas according to the unentangled observer, it hasn't.

If time is an emergent phenomenon, then how does the first event happen? If time does not yet exist, then there is no was to distinguish an event. By the parent's suggestion, time can only be propelled forward when already in motion, by the contribution of each new event. The very ideas of "first" and "new" presuppose the existence of time, and thus despite this likely significant scientific work, we continue to have a tautology until an instantiation somehow starts things off.

We are still, also, a long way away from understanding what causes wavefunction collapse, since the notion of observation is clearly ludicrous: there are no observers in the center of the sun, or on the far side of Jupiter, as two minor examples.

In the Copenhagen interpretation, one would say that according to the entangled observer the "wavefunction has collapsed" whereas according to the unentangled observer, it hasn't.

I prefer the Copenhagen interpretation, but this experiment is also interesting if we use the Many-Worlds interpretation. Then the God-like outside observer sees every possible quantum state and all of its outcomes simultaneously, as if they all have already happened. That sounds to me like a recipe for strict determinism.

Many-World is in fact strictly deterministic. It's considered one of it's advantages as QM becomes just like everything else in Physics.

Notice that strict determinism doesn't affect subjective free will. Instead of being a property of the world free will becomes a property of your internal representation of the world, pretty much like colors don't exist in the world, only in your brain, what evidently doesn't make them any less real for you and for anything you do based on them "being there".

And to me it seems that the statement "Colors exist in the world", intending to exclude perception of the world, doesn't make any sense. Photon energies exist in the world, but they aren't colors. Colors only exist in the context of perception.

Well, that's a great shame [wikipedia.org]. Whoever wrote the article on Wikipedia made no attempt to explain it in layman's terms. I give you:

In quantum gravity, the Wheeler–DeWitt equation[1] describes the quantum version of the Hamiltonian constraint using metric variables. Its commutation relations with the Diffeomorphism constraints generate the Bergmann-Komar "group" (which is the Diffeomorphism group on-shell, but differs off-shell).

Years of study no doubt required in order to even attempt to understand wha

It's because the subject takes time to digest and respond to intelligently. As opposed to the usual "NSA is Monitoring My Brain" headline. It's nice to see this type of article, it's what brought me to slashdot so many years ago. I still come everyday hoping to see more stuff like this.

I can appreciate the "get off my lawn" sentiment as much as the next guy, but honestly I don't feel the/. experience has degraded that much since the old days. Is it different now from when I joined 15 years ago? Yeah, sure. But so am I. So's the world.... So what?

The thing I find consistent about/. and which keeps me coming back here is that I know I'll (almost) always find something interesting here, often something very interesting and/or enlightening. Sure, I may occasionally bitch and moan about the dupes and the mods, etc., but when I see a story that looks interesting and has a "healthy" discussion going, I'm pretty confident that reading that discussion will give me some new insights or information that I hadn't heard of before. Offhand, I can't think of many other "popular" websites I could say the same about.

Ah yes, their entire experiment was a farce and you have just caught them! No doubt your highly analytical mind was able to see past what these researchers' colleagues and reviewers thought to be science, but what you have now uncovered to be naught but a pile of nonsense. I can't wait until tomorrow when all the world's newspapers print headlines of your great acumen.

"Time, we know, is relative. You can travel light years through the stars and back, and if you do it at the speed of light then, when you return, you may have aged mere seconds while your twin brother or sister will have aged twenty, thirty, forty or however many years it is, depending on how far you traveled. This will come to you as a profound shock, particularly if you didn't know you had a twin brother or sister."

What I can't yet understand is how this experiment helps validate the theory of time as an emergent quantum phenomenon. It seems more like a demonstration than an experiment to me. What alternative theory is their experiment excluding?

I'm a physicist but that doesn't mean I understand any of this QM stuff. I have a feeling this is a little like experimentally demonstrating Bell's inequality -- one can do experiments whose results are consistent with predictions of QM, and in ways that one might expect other general classes of theories to differ even though you don't have a specific alternative theory to exclude. Most experiments are like this really. But in the case of this time-entanglement experiment I really don't see room for alternative predictions. I think the paper's title acknowledges this: "Time from quantum entanglement: an experimental illustration" (my emphasis).

I'm not saying that the experiment is in any way unhelpful or bad. It's a great idea, but I would not go so far as to say that this is "experimental evidence."

> god can not detect any change in the universe.No, a theoretical external observer who looks at things the same way we do, does not detect change. That this encompasses the concept of God is to be demonstrated.

On a side note, Christians will quote Mt. 10:30 and say their God is quite capable, and others may object that a hypothetical creator of an abstraction is not bound by the rules of the abstraction itself, so you cannot exclude any capability.

If you don't nurture them then yes they don't grow. You don't have to force things on them but rather encourage their natural want to learn.

Now having a child (3 years old at the moment) i'm amazed at how quick they can learn, and feel sorry for children who's Parents don't interact with them and teach them. Too many parents want the schools to do everything for them, yet it is what they do outside of school which has the greatest impact to what they learn.

We are lucky, we don't say "Damn, I wasn't that dumb when I was that age!" instead my wife and I both go "Damn, he is smart, smarter than either of us at that age." and as long as we keep constantly feed him new ideas and information and reinforce it he will continue to be smarter than we were or are.

Again, just for the soapbox, the fact that children on average are getting "dumber" is completely the fault of their Parents.

Sadly, it's becoming well nigh impossible to find a decent chemistry set, electronics kit, meccano set, or even a generic Lego set. Everything is either excessively "safened" or themed to the point of monotony.

Well, we don't have those now (but they were already watered down - literaly, in the case of the chemistry set - by my time, are you sure you are not romanticizing it?), but now we have PCs, arduinos (or Pis if you need something faster), and 3D printers.

Yeah, they are not the same thing, but I guess that's exactly the point.

Amazon sells large boxes of generic Legos. It also sells the same electronics and chemistry kits I played with as a kid. Beyond that, it also sells actual lab equipment, chemical reagents, breadboards, soldering kits, and electronic components.

And don't forget the joy of pouring over the counter muriatic acid on aluminum foil, how easy it is to make a surprisingly potent explosive out of over the counter batteries and hydrogen peroxide, how much one can learn about orbital and collision dynamics playing Angry Birds Space, and the fact that kids now have nearly instant access to all of human thought and knowledge not actively covered by copyright (and summarized access to much of that!).

What they lose from not building a crystal radio or tinkering with cars (that have grown so complex that they are sadly no longer particularly tinkerable) they gain building a functional social network and tinkering with electronic devices that were pure science fiction for the first half of my life. To the extent that complexity of environment stimulates growth of intelligence as a possible partial explanation of the Flynn effect (and more, there are other metrics) children today grow up in very complex environments and do different things within it than we did.

It is thus silly to judge one generation in terms of the metrics of a previous one, especially a previous one that grew up in an entirely different political/historical context. Most of us would truly suck at stalking a deer armed only with a bow we made ourselves using nothing but a stone knife and arrows tipped with arrowheads we chipped out of river rocks. Most of us would simply die if we were dumped into the wild to survive a winter. We are therefore idiots by the standards of, say, 12,000 years ago. I suspect most of us would struggle with political dynamics from the feudal era and would rapidly find ourselves enslaved or hung if dropped into the world 1000 years ago. My own kids don't appreciate the stresses associated with growing up in the middle of a cold war that meant that every day there was a finite chance of the world of the survivors of a nuclear exchange regressing 1000 years overnight. I struggle to appreciate the stresses THEY experience growing up in a world that increasingly concentrates power in a hidden class of elites that have turned government into theater and that manipulate world-spanning conflicts between insane mythologies or hypothesized world-spanning disasters into excuses for concentrating ever more wealth and power in the hands of a criminal class that grew rich on laundered money in my lifetime.

When people ask me why I'm a theological noncognitivist, I ask them if their God needs to be omniscient and omnipotent in every universe in an infinite multiverse or if it'd be OK if thier God is a pimply-faced youth in another.

Typically, they have no idea what I'm talking about, and probably just assume I'm nuts.

When they say God must be omniscient, omnipotent and omnibenevolent...I ask 'isn't 2 out of 3 good enough'?The 3rd is a bit wishywashy anyway. What's benevolent in the opinion of some people won't be in the eyes of others.

So, the question of whether a tree falling in the woods makes a sound if there is nobody there to hear it is moot, because without anyone there to hear it, the tree wouldn't exist at all? Schroedinger's cat isn't both alive and dead, it isn't even in the box?

I read this essentially as saying that without an observer, time does not exist. Essentially, a "god-like" observer does not observe any change unless he or she becomes entangled in the universe he or she is observing. That universe, therefore, is without change, and therefore timeless. However, observers that are entangled within the universe (as we are), observe change and thus the universe (to them) has time.

This sounds a fair bit like some of the effects of relativity (on the train the shots appear simultaneous...on the ground they do not).

What is most intriguing to me, though, is that if the universe is both timeless (from the outside) and has time (from the inside), is it possible for us to gain the outside perspective (or any information about that timeless perspective). This shouldn't necessarily be impossible - we would need to not become entangled in the thing we are trying to observe (which we can easily do). Perhaps observing the surrounding universe would give unentangled information about the experiment in question, and thus give us a glimpse of the future?

Just keep in mind that an 'observer' does not mean a conscious entity. An observer, in the quantum mechanical sense, is more accurately an "interactor", as in anything that interacts with it. Which, when put into those terms, their thought process in this paper is much clearer: without interaction there is no way to determine if time has passed, if there's no way to tell if time is passing... it may as well not be.

...how this is related to the fact that the speed of light is the only true (known) constant in the universe.

for example...you are on a train going 50 km/hr north...you throw a ball 30 km/hr north and the ball is now going 30 km/hr north relative to you and 80 km/hr to a stationary observer...standard stuff.

BUT...you are on a light beam going 0.5c (half the speed of light) with a flashlight in your hand...you turn on the light...how fast is that light coming out of your flashlight going relative to you and our stationary observer?

well...relative to you its going...the speed of light...to the observer?

this is where it all gets weird...to the observer its going..the speed of light!

There are other physical constants, too. The charge of the electron for one and Plank's constant for another. The reality of a 'physical constant' is that it is just a ratio of one measured quantity in the observed Universe to another measured quantity that is always the same, so is sort of a conversion factor between physical observables which are somehow tightly related (not a great explanation, I know).
As for your light from the flashlight story -- there is no easy explanation because the easy explanations all depend on things behaving as we have grown up observing and internally modeling them in our low energy, slow speed existence. The explanation is just that at high relative speeds between observers the measurements of time and distance mix into each other such that each observer will always observe a light beam (in a vacuum) to be at 1.0c no matter what the speed of its source. A slightly deeper explanation is that time and 3 dimensional space form a four dimensional manifold (fancy name for something which local coordinates can be mapped to a flat space) in which the mix of time and space dimensions depends on the motion of the observer (actually reference frame of the observer). Relativistic effects are beyond the classical existence we model in heads growing up and so require math to take us beyond intuitive notions, that's about all I've got on the issue.

Your watch measures time, so you can use it to calculate how fast the light comes out of your torch by timing how long it takes to travel a distance, and you have a meter stick to measure just that.

When you are traveling fast, your watch slows down, and your meter rule gets shorter. However you don't notice this, as your own internal body's clock slows, and you yourself gets shorter in exactly the same proportions. But, when you measure the speed of light, coming out of the torch, now with your slower watch, and shorter meter stick, everything just adds up and you calculate the light to be traveling at the speed of light, EVEN THOUGH, the light, relative to you is now traveling just.5c.

The person you have just passed sees your watch, and meter rule, and thinks you've made a mistake, because your rule is longer and your watch ticks slower. He sees you measuring the speed of light coming from your torch. To him, he sees the light is coming out of your torch at.5c, but can see you (inaccurately) measuring it....and working it out to be 1c because you've measured it over a shorter distance using a slower watch.

When he measures the speed of the light coming out of your torch passing him, he also works it out to be going at light speed.

So there you go. There is no paradox. Light is going at the same speed regardless of if you are moving or not. The only difference is that your movement causes things like slowdown of time, and length change, which means that you are unable to calculate the "proper" relative speed of light, which would be.5c.......any attempt at measuring it, always comes out at 1c.

OR.....the more usual way of putting it is just make the speed of light constant, regardless of your speed, and alter the other things such as time, and length, to make your speed calculations always come to 1c.

(the following has turned into far more of a ramble than I first expected. I hope at least some of it makes sense)

But, if you must, it helps me to remember that the only absolute is spacetime. How you divide that up into space and time is dependent on your path through it.

If you were asked to divide a field into a coordinate grid, you might choose an arbitrary direction and then divide it up left-right and forward-backward from there. Someone else might face a different a direction and do the same thing - a different grid, but also a perfectly valid way to divide up the field.

So it is, sort of, with spacetime. But we don't choose our direction - instead it depends on our motion. If you're moving relative to another person, a bit of what they'd call space overlaps with a bit of what you'd call time, just as in the field where a bit of what they might call left-right overlaps with what you call forward-backward. There's a negative sign in the equations somewhere that puts the brakes on things though, and means you can't accelerate to the speed of light relative to anyone else without expending an infinite amount of energy. In Greg Egan's Clockwork Rocket series, the negative sign acts is switched with a positive one, so it's more like the easy-to-imagine field, and by accelerating one can completely swap what your home-bound friend would call time for a spatial dimension. Once they have accelerated enough, the travelling explorers can continue to experience time while none at all passes on their home planet. I think the implication is that by accelerating yet further, one could easily travel back in time. In fact, the danger in the story is from objects - quite possibly another otherwise perfectly ordinary solar system - travelling at right angles to the protagonist's home system - effectively at infinite speed.

The next brain-melting thing to consider is that, perhaps, everything moves at the speed of light - not through space, but through spacetime. But because most of the stuff we're familiar with - the Earth, the stars, etc - shares roughly the same path through spacetime, we don't experience it like that. All of our speed is taken up with travel into the future. We could swap a bit of it for travel through space if we accelerate. Without relativity, you could expect to travel for ten years there-and-back-again and find that ten years have passed at home. If you consider the simple field "swap" situation, you might conclude that by swapping some of your travel through time for travel through space, you'd find yourself less far into the future when you got back. But then that niggly negative sign comes into play - it makes me think of time as sort of 1/space - which means you actually find yourself more far into the future when you get back. Hence the twin paradox, where you find your Earth-bound friends have aged more than you have.

In the case of the photon, which uses up all of it's speed travelling through space, no time ever passes for it.

Any questions? No? Good. I'm off to catch up on the few hours of sleep I missed last night. Does it show?

You (as are most people with a poor grasp of these physics because of some shitty analogy someone used to explain it to them) are making the common mistake that the person with the flashlight in hand would think the light is traveling at 1c away from him (total of 1.5c) but they wouldn't see any such thing.

Yes they would see it traveling away at 1c - but the velocities don't sum like that. Due to time dilation, you're also experiencing time at a different rate than a stationary observer. The net effect is that you both see the light traveling at 1c.

To extend the analogy, suppose both people also have a stopwatch which starts timing at the exact moment when the person who's moving at 0.5c fires a pulse of light in the same direction as his movement. After the observer's stopwatch has reached 1 second, freeze everything and see where everyone is. The person who's moving at 0.5c has moved half the distance light travels in 1 second, obviously; about 149 896 km. The pulse of light has moved twice as far, about 299 792 km.

To the outside observer, the light has traveled 299 792 km in 1 second, i.e. it is moving at 1c.

The moving person, saw it travel only half as far relative to him - only 149 896 km - yet, because he's experiencing time at a different rate, his stopwatch has only ticked off 0.5 seconds. So from his perspective, the light has traveled 149 896 km in only 0.5 seconds, i.e. it is moving at 1c.

The basic answer and explanation is that the answer depends on your frame of reference. There's nothing in special (or general) relativity that stops the distance between A and B, as observed by a static spot X from increasing at 1.8*c. A and B don't see that; and more important, no information is transmittable from A to B (in any reference frame) faster than 1*c .

Here's a perfectly stupid question that probably does a good job of highlighting how little I know about this topic: So they are saying time is an emergent property that occurs when only one particle out of a entangled pair is observed. Does this mean that all objects in our universe must therefore be composed of particles that are somehow entangled with other particles located elsewhere (since all of the objects that we observe appear to be subject to time)? Even when we perform measurements at a particl

Most of this has been known and stated fairly clearly in the quantum theory of open systems for some time now. The Nakajima-Zwanzig (generalized master) Equation is derived based on the assumption of a "universal" quantum description that is partitioned into "system" and "everything else", with a projection of all dynamics from everything else onto the system variables. The universe is, of course, completely deterministic, but entropy (and hence "time" as an arrow) enters the system from the incomplete information available on the system "bath", everything else.

The proper treatment of this completely eliminates the common quantum "paradoxes" such as Schrodinger's Cat because one can clearly see where one makes an incorrect assumption about the possibility of quantum entanglement of the cat and the microscopic decay process independent of "everything else". The entire "system" consisting of cat and box is coupled to the rest of the Universe and the apparently "purely random" decay that creates the supposedly tangled state that is resolved by opening the box is continuously resolved because the box and all of its contents is already tangled, so to speak, with everything else. It also helps to properly view and include time-reversibility in the description and not treat the quantum process of measurement non-relativistically and semi-classically. The same thing is true of the EPR paradox -- if it is treated relativistically there can obviously be no such thing as wavefunction collapse per se with some sort of transluminal communication of phase information, because the time reversal of this process makes no sense at all. The GME resolves this entirely because it correctly describes the infusion of classical entropy in a measurement process from the bath in an e.g. thermodynamic state within e.g. the random phase approximation.

Personally, I think the Nakajima-Zwanzig treatment and master equations are one of the most neglected areas of quantum theory, often completely untaught in graduate-level quantum series. It is one of the better ways to rigorously derive things like spontaneous emission and in the process explain a lot of things about the process that are otherwise mysterious, such as how "exponential decay" arises from the coupling of a two-level quantum emitter to a multimode bath (and how it does NOT occur if one, for example, couples a two-level quantum emitter to a single field mode). Loudon has a nice discussion of this point, and Agarwal describes the application of the GME to spontaneous emission including radiative shift. The outcome of this approach in quantum mechanics is often to transform exponential processes that typically move one out of the basis one begins in almost instantly (entanglement) to projective dynamics within the basis and with e.g. discrete dynamical transitions replacing cats that are half dead or half alive in an entangled state, a Langevin approach where the actual system really does either kill the cat or doesn't, at a particular time, with the correct probability distribution for an ensemble of diabolical cat-killing engines, because the rest of the Universe always functions as a "measuring apparatus" -- one cannot "disentangle" the cat, the poison, the radioactive source from the Universe by merely putting it in a box, and at the instant of the cat's death the future time evolution of the entire Universe is unique to this and only this outcome.

You can see some small part of the malaise that infects the terminology of quantum theory in the phrase above: "An external god-like observer sees no difference" -- the hardest single thing one has to deal with when correctly considering the quantum description of the Universe is the notion that there is no outside, most especially no outside from which the inside can be "seen". Seeing is the exchange of information, mediated by a field interaction. The Universe cannot possibly be "seen from the outside" because if the "outside" in question can see it at all, it is a part of it. It cannot

" The universe is, of course, completely deterministic, but entropy (and hence "time" as an arrow) enters the system from the incomplete information available on the system "bath", everything else."

Saying that the universe is "completely deterministic" is rather disingenuous, considering the fairly huge amount of evidence to the contrary.

"The proper treatment of this completely eliminates the common quantum "paradoxes" such as Schrodinger's Cat because one can clearly see where one makes an incorrect assumption about the possibility of quantum entanglement of the cat and the microscopic decay process independent of "everything else". The entire "system" consisting of cat and box is coupled to the rest of the Universe and the apparently "purely random" decay that creates the supposedly tangled state that is resolved by opening the box is continuously resolved because the box and all of its contents is already tangled, so to speak, with everything else."

You take the Schrodinger's Cat "paradox" far to literally. Old Ernst intended it as a thought experiment, not a real one. And in that experiment, the contents of the box were presumed to be "disconnected" from the rest of the universe... any form of entanglement whatsoever. Your argument relies on re-defining the whole problem to fit your explanation. (Readers should

Except that this doesn't address whether or not the Universe is non-deterministic. It addresses whether or not one can perform a certain set of measurements on a tiny subset of the Universe -- where we could then spend a lot of energy speaking about just what a "measurement" is and how to define it and build an algebra associated with it -- and then make a unique prediction about the outcome of a second set of measurements made in the future. Or, we could find a copy of Julian Schwinger's classic book "Qu

Jesus said: If they say to you: Whence have you come?, say to them: We have come from the light, the place where the light came into being of itself. It [established itself], and it revealed itself in their image. If they say to you: Who are you?, say: We are his sons, and we are the elect of the living Father. If they ask you: What is the sign of your Father in you?, say to them: It is movement and rest.

In this case, the observer cannot detect any difference between the photons without becoming entangled with one or the other. And if there is no difference, the system appears static. In other words, time does not emerge.

This is the kind of in your face bullshit I have come to expect from a certain crowd of attention whores who regularly abuse terms like phase velocity and negative absolute temperatures to attract undue attention to their Sci-Fi ish ramblings which in reality are quite mundane.

Why yes dude you can't make a measurement without effecting what is being measured... newsflash from a century ago.

Since you can't measure something without changing it... you make the following jaw dropping assumption "And if there is no difference" to get to your assumption..

"the system appears static. In other words, time does not emerge."

"In other words" if you ASSume there is no difference time does not emerge.

It's very possible that the development of language in humans sort of locked us into the concept of time. For further reading, some of which sounds insane, look into pigeons and their homing instincts to see how other animals aren't necessarily perceiving time in the way that we do.

Animals do have some concept of time, as they have the concept of both position and velocity, and can extrapolate the relation between the two over time. For example, a dog can instinctively judge its jump so that it intercepts a thrown frisbee, likewise birds of prey hunting birds or fish.They may not be able to cogitate over the concepts they use, unlike us humans, but they can certainly put them into use.

Okay, to explain more fully: The second law states that entropy always increases over time (in a closed system). So nature very much does care about time - the progression of the three-dimensional state of the universe depends on the progression of time.

The direction of time is not arbitrary or human-defined. The other three dimensions are arbitrary, so far as we know; it doesn't matter whether you define those three dimensions relative to earth or the sun or the galaxy or whatever, and it doesn't matter

After reading a lot on this is that sometimes an issue becomes a problem without reason.

Now, time is ONLY a man made measure - a measure between events. Nature/the universe doesn't know what time is nor cares about it. It is only us humans that need to try to explain time dilation and various other 'time issues' to make the maths work. Remove time, and I bet it will balance these equations.

Time cannot run backwards,as there is no such thing as time except in the human brain and the human concept of measuring changes.

Nature doesn't care about time? Tell that to the laws of thermodynamics. Entropy only goes one way.

If you watch a video of a ball rolling on a desk, you can't tell just by the video whether time has been reversed. The physics governing that motion don't care about time. If you watch a video of an egg being shattered, you'll know when the video is reversed. You know all the contents of the egg can't spontaneously get back together as time moves forward. That would be going to a much more well-ordered state.

Also, the GPS device you use to triangulate your position and navigate to your destination? Well, consider that relativity tells us that the satellites zooming up above us have slower ticking clocks. They're actually moving through time slower than you are, and our current GPS accuracy wouldn't be achievable if we didn't take that into account.

Speed of light delays in gigahertz CPUs are special relativity. Speed of light delays in transoceanic online gaming are special relativity. Speed of light delays between the stock exchange and the high frequency trading equipment is special relativity, but that's not "consumer use" except that HFTs are using the consumer.

Well, consider that relativity tells us that the satellites zooming up above us have slower ticking clocks.

Actually, the GPS satellite clocks run 38 microseconds faster than ground based clocks.This is because they are not moving fast enough (special relativity: faster means slower clock) to counter the general relativistic effects (stronger gravitational field means slower ground clocks).Both clocks seem to be slower for an observer in free space.http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html [ohio-state.edu]